Technical Abstract:
Developing functional ingredients from this underutilized fish may offer an under used economic opportunity for the Alaskan seafood industry. The specific objectives of this study were to develop protein powders from herring byproducts and arrowtooth flounder fillet and to evaluate some of their chemical, physical and functional properties. Three separate samples of each whole herrings (WH), herring fillets (HF), herring heads (HH), and herring gonads (HG) and arrowtooth flounder fillets (AF) were minced. Water was added to the mince in a (1:1, V/W) ratio and the mixture heated at 85oC for 60 minutes. Soluble protein was recovered by centrifugation from the mixture and freeze-dried. Proximate analysis was done on the freeze-dried protein powders, as well as analysis of the amino acid composition and mineral content. Functional properties of the protein powders measured include emulsion capacity (EC), emulsion stability (ES), nitrogen solubility index, fat absorption, and color. The freeze-dried arrowtooth and herring protein powders were white to lightly yellow and had a slightly fishy odor and taste. The protein powders prepared from AF, WH, HF, HH and HG, respectively, contained 85%, 76.2%, 75.9%, 74.3% and 65% protein; 1.2%, 3.9%, 3.9%, 4.0%, and 9.9% lipids; 10.4%, 14.7%, 14.5%, 14.7%, and 16.3% ash, and 4.3%, 5.5%, 5.0%, 6.7%, and 9% moisture. The fish protein powders had a desirable essential amino acid profile, while Ca, Na, Mg, K, P and S were major minerals found in the protein powders. The EC of protein powders were much greater than that of soy protein concentrate (74.6) but less than egg albumin (327.9). The ES of protein powers was similar to that of soy protein concentrate but lower than egg albumin. The nitrogen solubility of protein powders was comparable to that egg albumin. Herring and arrowtooth protein powders had greater fat absorption than soy protein concentrate. The conclusion is that the protein powders made from these under utilized fish have potential for use in human food, and in nutraceutical products due to their functional and nutritional properties.